Fix: clarify man page lttng.1

Backported to stable-2.3 and 2.4.

Fixes #689

Signed-off-by: David Goulet <dgoulet@efficios.com>
Fix: implicit conversion from enumeration

Backported to stable-2.3 and 2.4.

Fixes #759

Signed-off-by: David Goulet <dgoulet@efficios.com>